Photographic material and process (B)

ABSTRACT

Photographic compound (A) capable of releasing a photographically useful group by means of intramolecular nucleophilic displacement exhibits increased resistance to hydrolysis when the compound contains in a coupling position a coupling-off group represented by the formula: ##STR1## wherein Q, R q , R 1 , R 2 , R 3 , n and PUG are as defined in the application. Such a compound (A) is useful in a photographic silver halide material and process.

This invention relates to new photographic compounds that releasephotographically useful groups by means of intramolecular nucloophilicdisplacement during photographic processing and to photographicmaterials and processes using such compounds.

Various ways are recognized in the photographic art for release of aphotographically useful group (PUG) from a compound, such as a coupler,in a photographic material and process. For example, U.S. Pat. No.4,248,962, describes compounds that release photographically usefulgroups by means of an intramolecular nucleophilic displacement reactionin photographic materials. These compounds, particularly couplers,capable of releasing a photographically useful group in a photographicmaterial upon processing provide a degree of control over the timing andrate of release as well as the rate of diffusion and distance ofdiffusion of the photographically useful group in the photogaphicmaterial.

A need has existed for a compound, preferably a coupler, that not onlyprovides the described release of a photographically useful group, butalso provides increased resistance to hydrolysis during storage. A needhas also existed for increased acutance of an image formed in aphotographic material containing such a compound during processing.Moreover, such needs have existed with the added parameter that such acompound must not require significantly modifying the photographicallyuseful groups or the carrier compounds, such as the couplers, in a waythat would adversely affect the ultimate end use for which each isintended.

The present invention solves these problems by means of a photographicelement comprising a support, at least one photographic silver halideemulsion layer and at least one compound (A) of the formula CAR-LINK-PUGwhere CAR is a carrier moiety capable of releasing LINK-PUG duringphotographic processing upon reaction with oxidized developing agent;LINK-PUG is in turn capable of releasing a photographically useful group(PUG) by an intramolecular molecular nucleophilic displacement reaction;and LINK-PUG is represented by the formula: ##STR2## wherein Q is N orCR_(z) ;

R_(q) is alkyl, cycloalkyl, heterocyclyl or aryl, or R_(q) together withR₁, R₂ or R_(z) can represent the atoms necessary to complete anon-aromatic ring;

R_(z), R₁ and R₂ are independently alkyl, cycloalkyl, heterocyclyl, arylor hydrogen;

R₃ is alkyl, cycloalkyl, heterocyclyl or aryl;

n is 0 or 1; and the LINK moiety enables increased resistance tohydrolysis.

Since similar LINK moieties in which Q-R_(q) is methylene do not providethe required resistance to hydrolysis, as shown in the comparative datain the examples, it is thought that the presence of a bulky Q-R_(q)group adjacent to the carboxy group in the LINK moiety may aid thisimprovement. Examples of such LINK-PUG groups are represented by thefollowing: ##STR3## wherein PUG is as defined above.

A preferred compound (A) is a dye-forming coupler of the formCOUP-LINK-PUG in which COUP is a coupler moiety and LINK-PUG is acoupling-off group.

A process of forming an image having the described advantages comprisesdeveloping an exposed photographic element by means of a colordeveloping agent in the presence of described compound (A), particularlya coupler as described.

The compound (A), preferably a coupler, contains a coupling-off group-LINK-PUG that enables increased resistance to hydrolysis duringstorage. It also enables increased acutance of an image formed uponprocessing a photographic silver halide element containing the compound(A) when PUG is a development inhibitor moiety.

Illustrative preferred -LINK-PUG groups are represented by the formulas:##STR4## wherein R₄ is alkyl, such as alkyl containing 1 to 5 carbonatoms, or an electron density controlling group, that is an electronwithdrawing group or an electron donating group as known in the organiccompound synthesis art. These improvements for compounds of theinvention are demonstrated by the data in the photographic examples whencompared to couplers of the type described in U.S. Pat. No. 4,248,962.

The reaction of compound (A), preferably a development inhibitorreleasing (DIR) coupler, with oxidized color developing agent cleavesthe bond between the coupling-off group and the carrier portion of thecompound (A), preferably the coupler moiety (COUP). Then the bondbetween the photographically useful group and the remainder of thecoupling-off group is cleaved. Bond cleavage between the PUG and theremainder of the coupling-off group preferably does not involve theaction of oxidized color developing agent. The cleavage of the bondbetween the PUG and the remainder of the coupling-off group is enabledby an intramolecular nucleophilic displacement reaction. Tailoring thestructure of the LINK moiety to the requirements of a given PUG allowscontrol over timing and rate of release of the PUG. The sequentialcleavage of the bond between the coupling-off group and the carrierportion of the compound A and the bond between the PUG and the remainderof the coupling-off group is a characteristic feature of the compoundsas described.

Particularly useful compounds as described are couplers represented bythe formula: ##STR5## wherein R₄ is an electron density controllinggroup and

PUG is a photographically useful group.

Examples of useful electron withdrawing groups as described for R₄include: ##STR6##

Examples of useful electron donating groups as described for R₄ include:##STR7##

When PUG is a development inhibitor, for instance, useful release timesare generally achieved using electron withdrawing groups in R₄ if PUG isa mercaptotetrazole derivative.

As used herein the terms "coupler" and "coupler compound" refer to theentire compound, including the coupler moiety and the coupling-off groupincluding the PUG. The term "coupler moiety" refers to that portion ofthe compond other than the coupling-off group.

The coupler moiety (COUP) can be any moiety that will react withoxidized color developing agent to cleave the bond between the carboxyportion of the coupling-off group and the coupler moiety. The couplermoiety herein includes coupler moieties employed in conventionalcolor-forming couplers that yield colorless products on reaction withoxidized color developing agents as well as coupler moieties that yieldcolored products on reaction with oxidized color developing agents. Bothtypes of coupler moieties are well known to those skilled in thephotographic art.

The coupler moiety can be ballasted or unballasted. In can be monomeric,or it can be part of a dimeric, oligomeric or polymeric coupler, inwhich case more than one group containing PUG can be contained in thecoupler, or it can form part of a bis compound in which the PUG formspart of a link between two coupler moieties.

It will be appreciated that, depending upon the particular couplermoiety, the particular color developing agent and the type ofprocessing, the reaction product of the coupler moiety and the oxidizedcolor developing agent can be: (1) colored and nondiffusible, in whichcase it will remain in the location in which it is formed, (2) coloredand diffusible, in which case it may be removed during processing fromthe location where it is formed or allowed to migrate to a differentlocation, or (3) colorless and diffusible or non-diffusible in whichcase it will not contribute to image density.

The coupling-off group is joined to the coupler moiety at the couplingposition of the coupler moiety. The coupling-off group is released fromthe coupling position by oxidative coupling reactions known in thephotographic art.

As used herein, the term "intramolecular nucleophilic displacementreaction" means a reaction in which a nucleophilic center of a compoundreacts directly, or indirectly through an intervening molecule, atanother site on the compound, that is an electrophilic center, to effectdisplacement of a group or atom attached to the electrophilic center.Such compounds have a nucleophilic group and electrophilic groupspacially related by the configuration of the molecule to promotereactive proximity. The electrophilic group and the nucleophilic groupare located in the coupling-off group as described so that a cyclicorganic ring, or a transient cyclic organic ring can be easily formed byan intramolecular reaction involving the nucleophilic center and theelectrophilic center.

A nucleophilic group is understood to be a grouping of atoms one ofwhich is electron rich. This atom is referred to as the nucleophiliccenter. An electrophilic group is understood to be a grouping of atomsone of which is electron deficient. This is referred to as theelectrophilic center.

The PUG can be any group that is typically made available in aphotographic element in an imagewise fashion. The PUG can be aphotographic reagent of a photographic dye. A photographic reagentherein is a moiety that upon release further reacts with components inthe photographic element, such as a development inhibitor, a developmentaccelerator, a bleach inhibitor, a bleach accelerator, a coupler (forexample, a competing coupler, a dye-forming coupler, or a developmentinhibitor releasing coupler (DIR coupler), a dye precursor, a dye, adeveloping agent (for example, a competing developing agent, adye-formng developing agent, or a silver halide developing agent), asilver complexng agent, a fixing agent, an image toner, a stabilizer, ahardener, a tanning agent, a fogging agent, an ultraviolet radiationabsorber, an antifoggant, a nucleator, a chemical or spectral sensitizeror a desensitizer.

The PUG can be present in the coupling-off group as a preformed speciesor it can be present in a blocked form or as a precursor. The PUG can befor example a preformed development inhibitor or the developmentinhibiting function can be blocked by being the point of attachment tothe carbonyl group bonded to PUG in the coupling-off group. Otherexamples are a preformed dye, a dye that is blocked to shift itsabsorption, and a leuco dye.

Preferred compound (A) is a photographic coupler containing a couplermoiety and a PUG containing a hetero atom from Group VA or VIA of thePeriodic Table having a negative valence of 2 or 3 bonded to the carbongroup of the coupling-off group.

There follows a listing of patents and publications which describerepresentative COUP groups useful in the invention. Also listed arestructures of preferred COUP and PUG groups. In these structures Yrepresents, in the case of a dye forming coupler that is useful withcouplers according to the invention, a hydrogen atom or a coupling-offgroup as described. In the case of couplers according to the invention,Y represents ##STR8## as defined above.

I. COUP's

A. Couplers which form cyan dyes upon reaction with oxidized colordeveloping agents are described in such representative patents andpublications as: U.S. Pat. Nos. 2,772,162; 2,895,826; 3,002,836;3,034,892; 2,474,293; 2,423,730; 2,367,531; 3,041,236; 4,333,999 and"Farbkuppler-eine Literaturubersicht," published in Agfa Mitteilungen,Band III, pp. 156-175 (1961).

Preferably such couplers are phenols and naphthols which form cyan dyeson reaction with oxidized color developing agent. Structures ofpreferred such couplers are: ##STR9## where R₆ represents a ballastgroup, and R₇ represents one or more halogen such as chloro or fluoro;alkyl such as methyl, ethyl, butyl; or, alkoxy, such as methoxy, ethoxy,butoxy groups.

B. Couplers which form magenta dyes upon reaction with oxidized colordeveloping agent are described in such representative patents andpublications as: U.S. Pat. Nos. 2,600,788; 2,369,489; 2,343,703;2,311,082; 3,152,896; 3,519,429; 3,062,653; 2,908,573 and"Farbkuppler-eine Literaturubersicht," published in Agfa Mitteilungen,Band III, pp. 126-156 (1961).

Preferably, such couplers are pyrazolones and pyrazolotriazoles whichform magenta dyes upon reaction which oxidized color developing agentsand have the Y attached to the coupling position.

Structures of preferred such coupler moieties are: ##STR10## where R₆and R₇ are chosen independently to be a ballast group, unsubstituted orsubstituted alkyl, phenyl or substituted phenyl.

C. Couplers which form yellow dyes upon reaction with oxidized and colordeveloping agent are described in such representative patents andpublications as: U.S. Pat. Nos. 2,875,057; 2,407,210; 3,265,506;2,298,443; 3,048,194; 3,447,928 and "Farbkuppler-eineLiteraturubersicht," published in Agfa Mitteilungen, Band III, pp.112-126 (1961).

Preferably such yellow-dye forming couplers are acylacetamides, such asbenzoylacetanilides and pivaloylacetanilides, and have the Y groupattached to the coupling position, that is the active methylene carbonatom.

Structures of preferred such coupler moieties are: ##STR11## where R₆ isas defined above and R₇ and R₈ are hydrogen or more or more halogen,lower alkyl, such as methyl and ethyl, lower alkoxy, such as methoxy andbutoxy, or ballast groups, such as alkoxy of 16 to 20 carbon atoms.

D. Couplers which form colorless products upon reaction with oxidizedcolor developing agent are described in such representative patents as:U.K. Pat. No. 861,138; U.S. Pat. Nos. 3,632,345; 3,928,041; 3,958,993and 3,961,959. Preferably such couplers are cyclic carbonyl containingcompounds which form colorless products on reaction with oxidized colordeveloping agent and have the Y group attached to the carbon atom in theα-position with respect to the carbonyl group.

Structures of preferred such coupler moieties are: ##STR12## where R₆ isas defined above and n is 1 or 2.

E. Couplers which form black dyes upon reaction with oxidized colordeveloping agent are described in such representative patents as U.S.Pat. Nos. 1,939,231; 2,181,944; 2,333,106; and 4,126,461; German OLS No.2,644,194 and German OLS No. 2,650,764.

Preferably such couplers are resorcinols or m-aminophenols which formblack or neutral products on reaction with oxidized color developingagent and have the Y group para to a hydroxy group.

Structures of preferred such coupler moieties are: ##STR13## where R₉ isalkyl of 3 to 20 carbon atoms, phenyl or phenyl substituted withhydroxy, halo, amino, alkyl of 1 to 20 carbon atoms or alkoxy of 1 to 20carbon atoms; each R₁₀ is independently hydrogen, alkyl of 1 to 20carbon atoms, alkenyl of 1 to 20 carbon atoms, or aryl of 6 to 20 carbonatoms; and Rg is one or more halogen, alkyl of 1 to 20 carbon atoms,alkoxy of 1 to 20 carbon atoms or other monovalent organic groups.

PUG's

A. PUG's which form development inhibitors upon release are described insuch representative patents as U.S. Pat. Nos. 3,227,554; 3,384,657;3,615,506; 3,617,291; 3,733,201 and U.K. Pat. No. 1,450,479. Preferreddevelopment inhibitors are iodide and heterocyclic compounds such asmercaptotetrazoles, selenotetrazoles, mercaptobenzothiazoles,selenobenzothiazoles, mercaptobenzoxazoles, selenobenzoxazoles,mercaptobenzimidazoles, selenobenzimidazoles, oxadiazoles,benzotriazoles and benzodiazoles. Structures of preferred developmentinhibitor moieties are: ##STR14## where W₁ is unsubstituted orsubstituted alkyl, such as butyl, 1-ethylpentyl, and 2-ethoxyethyl, oralkylthio, such as butylthio and octylthio; R₁₁ and R₁₂ are individuallyhydrogen, alkyl of 1 to 8 carbon atoms such as methyl, ethyl, or butyl,phenyl or substituted phenyl; and R₁₃ and R₁₄ are individually hydrogenor one or more halogen such as chloro, fluoro or bromo; alkyl of 1 to 4carbon atoms, carboxyl, carboxy esters, such as --COOCH₃, --NHCOOCH₃,--SO₂ OCH₃, --OCH₂ CH₂ SO₂ CH₃, ##STR15## or nitro groups.

B. PUG's which are, or form, dyes upon release:

Suitable dyes and dye precursors include azo, azomethine, azopyrazolone,indoaniline, indophenol, anthraquinone, triarylmethane, alizarin, nitro,quinoline, indigoid and phthalocyanine dyes or precursors of such dyessuch as leuco dyes, tetrazolium salts or shifted dyes. These dyes can bemetal complexed or metal complexable. Representative patents describingsuch dyes are U.S. Pat. Nos. 3,880,658; 3,931,144; 3,932,380; 3,932,381and 3,942,987. Preferred dyes and dye precursors are azo, azomethine andindoaniline dyes and dye precursors. Structures of some preferred dyesand dye precursors are: ##STR16##

C. PUG's which are couplers:

Couplers released can be nondiffusible color-forming couplers, non-colorforming couplers or diffusible competing couplers. Representativepatents and publications describing competing couplers are: "On theChemistry of White Couplers," by W. Puschel, Agfa-Gevaert AGMitteilungen and der Forschungs-Laboratorium der Agfa-Gevaert AG,Springer Verlag, 1954, pp. 352-367; U.S. Pat. Nos. 2,998,314; 2,808,329;2,689,793; 2,742,832; German Pat. No. 1,168,769 and British Pat. No.907,274. Structures of preferred competing couplers are: ##STR17## whereR₁₇ is hydrogen or alkylcarbonyl, such as acetyl, and R₁₈ and R₁₉ areindividually hydrogen or a solubilizing group, such as sulfo,aminosulfonyl, and carboxy ##STR18## where R₁₉ is as defined above andR₂₀ is halogen, aryloxy, arylthio, or a development inhibitor, such as amercaptotetrazole, such as phenylmercaptotetrazole or ethylmercaptotetrazole.

D. PUG's which form developing agents:

Developing agents released can be color developing agents,black-and-white developing agents or cross-oxidizing developing agents.They include aminophenols, phenylene diamines, hydroquinones andpyrazolidones. Representative patents are: U.S. Pat. Nos. 2,193,015;2,108,243; 2,592,364; 3,656,950; 3,658,525; 2,751,297; 2,289,367;2,772,282; 2,743,279; 2,753,256 and 2,304,953.

Structures of preferred developing agents are: ##STR19## where R₂₁ ishydrogen or alkyl of 1 to 4 carbon atoms and R₂₂ is hydrogen or one ormore halogen such as chloro or bromo; or alkyl of 1 to 4 carbon atomssuch as methyl, ethyl or butyl groups. ##STR20## where R₂₂ is as definedabove. ##STR21## where R₂₃ is hydrogen or alkyl of 1 to 4 carbon atomsand R₂₄, R₂₅, R₂₆, R₂₇ and R₂₈ are individually hydrogen, alkyl of 1 to4 carbon atoms such as methyl or ethyl; hydroxyalkyl of 1 to 4 carbonatoms such as hydroxymethyl or hydroxyethyl or sulfoalkyl containing 1to 4 carbon atoms.

E. PUG's which are bleach inhibitors:

Representative patents are U.S. Pat. Nos. 3,705,801; 3,715,208; andGerman OLS No. 2,405,279. Structures of preferred bleach inhibitors are:##STR22## where R₂₉ is an alkyl group of 6 to 20 carbon atoms.

F. PUG's which are bleach accelerators: ##STR23## wherein W₁ ishydrogen, alkyl, such as ethyl and butyl, alkoxy, such as ethoxy andbutoxy, or alkylthio, such as ethylthio and butylthio, for examplecontaining 1 to 6 carbon atoms, and which may be unsubstituted orsubstituted; W₂ is hydrogen, alkyl or aryl, such as phenyl; W₃ and W₄are individually alkyl, such as alkyl containing 1 to 6 carbon atoms,for example ethyl and butyl; z is 1 to 6.

The Y and particularly the PUG are selected and prepared to adjust tothe activity of the adjoining carrier moiety, particularly a couplermoiety and the other groups of the coupler in order to optimize releaseof the PUG for its intended purpose. Accordingly, PUG groups ofdiffering structural types are useful which enable timing groups havinga range of activities. Various properties, such as pKa, are alsousefully considered in optimizing the selection of optimum groups for aparticular purpose. An example of such a selection could involve, forinstance, a benzotriazole moiety as a PUG. Such a benzotriazole moietycan be released too quickly from a timing group which involves anintramolecular nucleophilic displacement mechanism; however, thebenzotriazole moiety can be modified from ##STR24## in order to modifythe rate at which the benzotriazole moiety is cleaved from the Y.Another illustration of modifying the PUG involves changing, forexample, a mercaptotetrazole moiety from ##STR25## at elevated pH, suchas above about pH 10, wherein the --CH₂ O-- portion of the grouphydrolyzes rapidly leaving the remainder of the PUG free for itsintended purpose.

The photographic couplers of this invention can be incorporated inphotographic elements and/or in photographic processing solutions, suchas developer solutions, so that upon development of an exposedphotographic element they will be in reactive association with oxidizedcolor developing agent. Coupler compounds incorporated in photographicprocessing solutions should be of such molecular size and configurationthat they will diffuse through photographic layers with the processingsolution. When incorporated in a photographic element, as a generalrule, the coupler compounds should be nondiffusible, that is they shouldbe of such molecular size and configuration that they will notsignificantly diffuse or wander from the layer in which they are coated.

Photographic elements of this invention can be processed by conventionaltechniques in which color forming couplers and color developing agentsare incorporated in separate processing solutions or compositions or inthe element.

Photographic elements in which the compounds of this invention areincorporated can be a simple element comprising a support and a singlesilver halide emulsion layer or they can be multilayer, multicolorelements. The compounds of this invention can be incorporated in atleast one of the silver halide emulsion layers and/or in at least oneother layer, such as an adjacent layer, where they will come intoreactive association with oxidized color developing agent which hasdeveloped silver halide in the emulsion layer. The silver halideemulsion layer can contain or have associated with it, otherphotographic coupler compounds, such as dye-forming couplers, coloredmasking couplers, and/or competing couplers. These other photographiccouplers can form dyes of the same or different color and hue as thephotographic couplers of this invention. Additionally, the silver halideemulsion layers and other layers of the photographic element can containaddenda conventionally contained in such layers.

A typical multilayer, multicolor photographic element can comprise asupport having thereon a red-sensitive silver halide emulsion unithaving associated therewith a cyan dye image-providing material, agreen-sensitive silver halide emulsion unit having associated therewitha magenta dye image-providing material and a blue-sensitive silverhalide emulsion unit having associated therewith a yellow dyeimage-providing material, at least one of the silver halide emulsionunits having associated therewith a photographic coupler of theinvention. Each silver halide emulsion unit can be composed of one ormore layer and the various units and layers can be arranged in differentlocations with respect to one another.

The couplers of this invention can be incorporated in or associated withone or more layers or units of the photographic element. For example, alayer or unit affected by PUG can be controlled by incorporating inappropriate locations in the element a scavenger layer which willconfine the action of PUG to the desired layer or unit. At least one ofthe layers of the photographic element can be, for example, a mordantlayer or a barrier layer.

The light sensitive silver halide emulsions can include coarse, regularor fine grain silver halide crystals or mixtures thereof and can becomprised of such silver halides as silver chloride, silver bromide,silver bromoiodide, silver chlorobromide, silver chloroiodide, silverchlorobromoiodide and mixtures thereof. The emulsions can benegative-working or direct-positive emulsions. They can form latentimages predominantly on the surface of the silver halide grains orpredominantly on the interior of the silver halide grains. They can bechemically and spectrally sensitized. The emulsions typically will begelatin emulsions although other hydrophilic colloids are useful.Tabular grain light sensitive silver halides are particularly usefulsuch as described in Research Disclosure, January 1983, Item No. 22534and U.S. Pat. No. 4,434,226.

The support can be any support used with photographic elements. Typicalsupports include cellulose nitrate film, cellulose acetate film,polyvinylacetal film, polyethylene terephthalate film, polycarbonatefilm and related films or resinous materials as well as glass, paper,metal and the like. Typically, a flexible support is employed, such as apolymeric film or paper support. Paper supports can be acetylated orcoated with baryta and/or an α-olefin polymer, particularly a polymer ofan α-olefin containing 2 to 10 carbon atoms such as polyethylene,polypropylene, ethylene-butene copolymers and the like.

The compound (A), particularly photographic couplers as described, canbe used in photographic elements in the same way as photographiccouplers which release PUGs have previously been used in photographicelements. However, because of the improved ability to control therelease of the PUG, the couplers permit enhanced effects or moreselective effects. In addition, the couplers can be employed inapplications where conventional coupler have previously been employedand a separate component was employed to provide a PUG.

Depending upon the nature of the particular PUG, the couplers can beincorporated in a photographic element for different purposes and indifferent locations.

When the PUG released from the coupler is a development inhibitor, thecoupler can be employed in a photographic element like couplers whichrelease development inhibitors have been used in the photographic art.Couplers of this invention which release a development inhibitor can becontained in, or in reactive association with, one or more of the silverhalide emulsion units in a color photographic element. If the silverhalide emulsion unit is composed of more than one layer, one or more ofsuch layers can contain the coupler of this invention. The layers cancontain other photographic couplers conventionally used in the art. Thecoupling reaction using couplers of this invention can form dyes of thesame color as the color forming coupler(s) in the layer or unit, it canform a dye of a different color, or it can result in a colorless orneutral reaction product. The range of operation between layers of thedevelopment inhibitor released from the coupler of this invention can becontrolled by the use of scavenger layers, such as a layer of fine grainsilver halide emulsion. Scavenger layers can be in various locations inan element containing couplers of this invention. They can be locatedbetween layers, between the layers and the support, or over all of thelayers.

Couplers of this invention which release development inhibitors canenhance the effects heretofore obtained with DIR couplers since they canrelease a development inhibitor at a distance from the point at whichoxidized color developing agent reacted with the coupler, in which casethey can provide, for example, enhanced interlayer interimage effects.

Photographic couplers as described which release bleach inhibitors orbleach accelerators can be employed in the ways described in thephotographic art to inhibit the bleaching of silver or acceleratedbleaching in areas of a photographic element.

Photographic couplers as described which release a dye or dye precursorcan be used in processes where the dye is allowed to diffuse to anintegral or separate receiving layer to form a desired image.Alternatively, the dye can be retained in the location where it isreleased to augment the density of the dye formed from the coupler fromwhich it is released or to modify or correct the hue of that dye oranother dye. In another embodiment, the dye can be completely removedfrom the element and the dye which was not released from the coupler canbe retained in the element as a color correcting mask.

Couplers as described can be employed to release another coupler and thePUG. If the released coupler is a dye-forming coupler it can react withoxidized developing agent in the same or an adjacent layer to form a dyeof the same or a different color or hue as that obtained from theprimary coupler. If the released coupler is a competing coupler it canreact with oxidized color developing agent in the same or an adjacentlayer to reduce dye density.

Photographic couplers as described in which the PUG is a developingagent can be used to release a developing agent which will compete withthe color forming developing agent, and thus reduce dye density.Alternatively, the couplers can provide, in an imagewise manner, adeveloping agent which because of such considerations as activity wouldnot desirably be introduced into the element in a uniform fashion.

In chemical systems requiring timed release of a moiety as describedherein, the release mechanisms can be initiated by any means thatinitiates cleavage of the coupling-off group from the carrier moiety.Depending on the particular carrier compound, the desired end use of theactive moiety, the release mechanism can, for example, be initiated byreaction of the carrier compound with radiation, enzymes, moisture, acidor base, and/or oxidized reducing agent.

In the following discussion of suitable materials for use in theemulsions and elements of this invention, reference will be made toResearch Disclosure, December 1978, Item 17643, published by IndustrialOpportunities Ltd., Homewell Havant, Hampshire, PO9 1EF, U.K., thedisclosures of which are incorporated herein by reference. Thispublication will be identified hereafter by the term "ResearchDisclosure".

The photographic elements can be coated on a variety of supports asdescribed in Research Disclosure Section XVII and the referencesdescribed therein.

Photographic elements can be exposed to actinic radiation, typically inthe visible region of the spectrum, to form a latent image as describedin Research Disclosure Section XVIII and then processed to form avisible dye image as described in Research Disclosure Section XIX.Processing to form a visible dye image includes the step of contactingthe element with a color developing agent to reduce developable silverhalide and oxidize the color developing agent. Oxidized color developingagent to turn reacts with the coupler to yield a dye.

Preferred color developing agents useful in the invention arep-phenylene diamines. Especially preferred are4-amino-N,N-diethylaniline hydrochloride;4-amino-3-methyl-N,N-diethylaniline hydrochloride;4-amino-3-methyl-N-ethyl-N-β-(methanesulfonamido)ethylaniline sulfatehydrate; 4-amino-3-methyl-N-ethyl-N-β-hydroxyethylaniline sulfate;4-amino-3-β-(methanesulfonamido)ethyl-N,N-diethylaniline hydrochloride;and 4-amino-N-ethyl-N-(2-methoxyethyl)-m-toluidine di-p-toluenesulfonicacid.

With negative working silver halide. The processing step described abovegives a negative image. To obtain a positive (or reversal) image, thisstep can be preceded by development with a non-chromogenic developingagent to develop exposed silver halide, but not form a dye, and thenuniformly fogging the element to render unexposed silver halidedevelopable. Alternatively, a direct positive emulsion can be employedto obtain a positive image.

Development is followed by the conventional steps of bleaching, fixing,or bleach-fixing, to remove silver and silver halide, washing anddrying.

Compounds as described can be prepared by reactions and methods known inthe organic compound synthesis art. Typically, the couplers as describedare prepared in Scheme A by first attaching the LINK group to thecoupling position of the coupler moiety (COUP) without the PUG beingpresent. Then the product is reacted with an appropriate derivative ofthe PUG to form the desired coupler. Alternatively, PUG may be attachedfirst to the LINK group as in Scheme B, and then the LINK-PUG groupattached to COUP. The following description illustrates these synthesesin which ##STR26##

A nitrogen-blocking group B is first attached to amino acid S-1 bytreatment with S-2 and the resulting S-3 is allowed to react with thehydroxyl-coupler compound to produce S-4. The blocking group B(typically COOCH₂ Ph or CH₂ Ph) is then removed by hydrogenolysis togive the COUP-LINK moiety S-5. S-5 can also be made directly from S-1 byreaction with the hydroxyl-coupler compound, but yields and purity maysuffer. Treatment of S-5 with phosgene converts it to the correspondingcarbonyl chloride, which can further react with a given PUG to providethe desired COUP-LINK-PUG compound S-7. Alternatively, reaction of a PUGcarbonyl chloride with S-5 can give S-7 directly. ##STR27##

A given PUG group can be attached to a hydrazine compound S-8 byreaction with S-9. The resultant S-10 is then treated with phosgene togive the carbonyl chloride derivative S-11, which can further react withthe hydroxyl-coupler compound to give the desired COUP-LINK-PUG compoundS-12.

The following examples illustrate syntheses of particular compounds (A),especially couplers, as described:

Synthesis of Compound 2: ##STR28## PMT herein meansphenylmercaptotetrazole.

N-Benzylalanine (S-14)

L-Alanine (44.6 g, 0.5 mole)) was taken up in 250 mL 2N-NaOH to whichwas added benzaldehyde (50 mL, 0.5 mole). The resulting suspension wasstirred at room temperature for approximately 20 minutes. After thisperiod a pale yellow solution resulted. This solution was cooled in anice/acetone bath and sodium borohydride (5.7 g, 0.15 mole) added in 1.0g portions while keeping the temperature below 15° C. A large flask isnecessary as a good deal of foaming takes place during the course of thereaction. The above process was repeated with the same quantities ofbenzaldehyde and sodium borohydride. However, this time after theaddition of the sodium borohydride, the resulting solution was stirredfor about 11/2 hours at room temperature and then washed with either(100 mL, ×2). The ether extracts were discarded and the aqueous phaseacidified with 6N-HCl to pH 6-7. The product precipitated out of thesolution. The resulting mixture was left overnight in the refrigeratorand filtered the following morning. The product was washed with a littlecold water and air dried. Yield 67 g (75%).

N-Methyl-N-Benzylalanine (S-15)

The N-benzylalanine (1), (67 g, 0.374 mole) was taken up in formic acid(41 mL, 88%) and formaldehyde (37 mL, 38%) added. The resulting solutionwas heated on a steam bath for 11/2 hours. After this period the clearsolution was cooled and as much of the solvent as possible removed underreduced pressure. Removal of the water was aided by co-evaporation withmethanol. To the residual oil was added methanol (200 mL) and thesolution diluted with ether yielding the product as a fine white powder,63.7 g (88%).

N-Benzyl-N-Methyalanate Compound (S-17)

The 1.4-dihydroxynaphthalene (10.0 g, 20.34 mmol) was taken up in THF(150 mL) and ethyl acetate (200 mL). DCC (4.2 g, 20.34 mmol) andN-benzyl-N-methylalanine (2), (4.32 g, 22.37 mmol) added followed by theN,N-dimethylaminopyridine catalyst (300 mg). The reaction was left tostir at room temperature overnight. The following morning a thin layerchromatography analysis (silica gel, 15% ethyl acetate in hexane) showedthe reaction to be complete. The dicyclohexylurea was filtered off andthe filtrate taken to an oil under reduced pressure. This oil was takenup in 15% ethyl acetate in hexane, filtered and chromatographed oversilica gel eluting with the same solvent. The first major band wascollected to give the product which crystallized from hexane. Yield 6.5g (48%).

N-Methylalanate (S-18)

The N-benzyl-N-methylalanate (3), (2.0 g, 3.0 mmol) was taken up inacetic acid (50 mL), to which was added the catalyst, 10%-Pd-on-C (300mg), and the solution hydrogenated for 2 hours at 45 psi. After thisperiod a thin layer chromatography analysis (silica gel, 15% ethylacetate in hexane, and also ethyl acetate alone) showed no startingmaterial. The catalyst was filtered off and the acetic acid solutionpoured into water (200 mL) and extracted with methylene chloride (3×50mL). The organic extracts were washed with sodium bicarbonate (1×50 mL)and dried (MgSO₄). The solvent was removed to given an oil whichcrystallized from hexane. Yield 1.4 g (82%).

N-Methylalanate Carbonyl Chloride (S-19)

The N-methylalanate (9.7 g, 16.82 mmol) was taken up in dry THF (100 mL)to which was added the phosgene (100 mL of a 12% solution in toluene).The base, N,N-diethylaniline (DEA), (2.7 mL, 16.82 mmol) was then addedand the reaction stirred at room temperature for about 20 minutes. Atthe end of this period, the solvent was removed under vacuum to give anoil which was used as such in the next step.

Compound 2

The N-methylalanate carbonyl chloride (S-19), (17.34 mmol, prepared asdescribed above) was taken up in pyridine (100 mL), to which was addedthe phenylmercaptotetrazole (3.1 g, 17.34 mmol) and the reaction stirredat room temperature for several hours. A thin layer chromatographyanalysis (silica gel, 30% ethyl acetate in hexane) showed no startingmaterial but just one new major spot which was more polar than thestarting material. The pyridine was removed under reduced pressure, theoil taken up in ethyl acetate (100 mL), washed with 2N-HCl (2×100 mL),dried (MgSO₄) and then the solvent removed under vacuum to yield an oil.This oil was taken up in 30% ethyl acetate in hexane eluting with thesame solvent and the first major band collected. Yield 9.0 g (66%).

Calculated for C₄₃ H₅₂ N₆ O₆ S: %C=66.1, %H=6.7, %N=10.8, %S=4.1; Found:%C=66.0, %H=6.6, %N=10.6, %S=4.4

Synthesis of Compound 3: ##STR29##

Dimethylhydrazine dihydrochloride (10.0 g, 75.17 mmol), together withpotassium carbonate (11.5 g, 82.64 mmol) were taken up in water (mL),and stirred at room temperature. To this solution was then added thebis-PMT-CO (2.4 g, 7.52 mmol) in ethyl acetate (100 mL) dropwise, overabout a one-hour period. The reaction was stirred at room temperatureovernight. Following morning the aqueous layer was run off and theorganic layer washed with 10% sodium carbonate (2×50 mL). A thin layerchromatography analysis (silica gel, ethyl acetate) showed only one newspot. The solution was dried (MgSO₄) and concentrated. The productcrystallized out on addition of heptane, it was filtered off, air driedto give 1.25 g of the hydrazide (1), 63%.

The hydrazide (1.2 g, 4.54 mmol) was taken up in methylene chloride (20mL) and the base, N,N-diisopropylethylamine (0.8 mL, 4.54 mmol), wasadded followed by the phosgene (19 mL of a 12% solution of phosgene intoluene, 22.70 mmol). The reaction was stirred for about 30 minutes atroom teperature, after which a thin layer chromatography analysis(silica gel, ethyl acetate) showed no starting material. The solvent wasremoved under reduced pressure and the crude carbonyl chloride (2) usedas such in the next step.

The above carbonyl chloride (about 4.54 mmol) together with the1,4-dihydroxynaphthalene (3), (2.23 g, 4.54 mmol) were taken up inmethylene chloride, (50 mL). To this solution was then added the base,N,N-diisopropylethylamine (0.8 mL, 4.54 mmol), followed by a catalyticamount of N,N-dimethylaminopyridine (about 10 mg). The reaction wasstirred at room temperature for about one hour. At the end of thisperiod a thin layer chromatography analysis (silica gel, 30% ethylacetate in hexane) showed a new material present. The reaction waswashed with 2N-HCl (xl, 50 mL), dried magnesium sulfate) and the solventremoved under vacuum. The residual oil was chromatographed over silicagel eluting 30% ethyl acetate in hexane containing a few percent ofmethylene chloride to aid dissolution. The main band was collected,concentrated and recrystallized from ethyl acetate/hexane. Yield 780 mg,22%.

Calculated for C₄₂ H₅₁ N₇ O₆ S: %C=64.5, %H=6.6, %N=12.5, %S=4.1; Found:%C=64.6, %H=6.4, %N=12.4, %S=4.4

The following examples further illustrate the invention.

EXAMPLES 1-11:

The half-life for release of the development inhibitor PUG from each DIRcompound was determined in solution as a means for predicting therelative release rates when incorporated in film coatings. All reactionswere carried out at a measured pH of 10.0+/-0.2 in aqueous 3% TritonX-100 (Triton X-100 is a trademark), ionic strength 0.375.Concentrations were chosen so that dye formation from COUP and LINK-PUGliberation would be complete in a fraction of a second. The rate of thecoupling reaction and the limitations of hand pipetting imposed a onesecond lower limit on the range of half-lives which could be determinedby this method.

To a scintillation via with magnetic stirbar were added coupler stock(1.0 mL of 2 mMolar solution in aqueous 12% Triton X-100), pH 10phosphate buffer (1.0 mL, ionic strength 1.5), and aqueous CD-2developer compound (1.0 mL of 2 mMolar solution). At time zero, aqueousferricyanide (1.0 mL of 4 mMolar solution) was added to the rapidlystirred mixture, allowed to react for variable time periods, and thenquenched with aqueous HCl (1.0 mL of 1.0 mMolar solution). The amount ofreleased development inhibitor was determined by high pressure liquidchromatography and a first order rate constant k for inhibitor releasewas calculated from the inhibitor concentration vs. reaction time data.The half-life of release reported in Table I was then calculated usingthe formula t_(1/2) =ln (2)/k.

Kinetics of Coupler Decomposition in Acetonitrile/H₂ O

An acetonitrile solution of coupler (2 mL, 1×10⁻³ M) was mixed withaqueous potassium hydroxide (2 mL, 0.100N) and the time noted. Theresulting solution was rapidly transferred to a quartz UV cell and thedecrease in absorption due to coupler anion was monitored as a functionof time. The mixture pH was measured before and after spectroscopicmeasurements. A first order rate constant for reaction of coupler anionk_(decomp), was calculated from absorbance vs. time data. In cases wherean insignificant change in the absorbance spectrum occurred after ≧15 h,the mixture was analyzed by HPLC to verify and quantify the presence ofunreacted coupler. Half-lives for coupler hydrolytic decomposition werecalculated with the expression t_(1/2), hydr.=ln (2)/k_(decomp). Theresults are reported in Table I. ##STR30##

                                      TABLE I                                     __________________________________________________________________________    LINK = L-1                                                                                                    t.sub.1/2                                                                           t.sub.1/2                                                               Hydr. Release                                 Example  Compd.                                                                             Q--R.sub.q                                                                           n R.sub.3                                                                             PUG                                                                              (Seconds)                                                                           (Seconds)                               __________________________________________________________________________    1 Comparison                                                                           C-1  --CH.sub.2 --                                                                        0 --CH.sub.3                                                                          PMT                                                                              32    700                                     2 Invention                                                                            1    --CH(CH.sub.3)--                                                                     0 --CH.sub.3                                                                          PMT                                                                              100   60                                      3 Invention                                                                            2    --N(CH.sub.3)--                                                                      0 --CH.sub.3                                                                          PMT                                                                              4080  n/a                                     4 Comparison                                                                           C-2  --CH.sub.2 --                                                                        0 --Ph  PMT                                                                              190   20                                      5 Comparison                                                                           C-3  --CH.sub.2 --                                                                        1 --Ph  PMT                                                                              840   13000                                   6 Invention                                                                            3    --C(CH.sub.3).sub.2 --                                                               1 --Ph  PMT                                                                              40000 300                                     7 Invention                                                                            4    --C(CH.sub.3).sub.2 --                                                               1 --Ph--3-Cl                                                                          PMT                                                                              31000 28                                      8 Comparison                                                                           C-4  --CH.sub.2 --                                                                        0 --CH.sub.3                                                                          DPB                                                                              n/a   1100                                    9 Invention                                                                            5    --CH(CH.sub.3)--                                                                     0 --CH.sub.3                                                                          DPB                                                                              n/a   3                                       10                                                                              Comparison                                                                           C-5  --CH.sub. 2 --                                                                       0 --CH.sub.3                                                                          DCB                                                                              n/a   53                                      11                                                                              Invention                                                                            6    --CH(CH.sub.3)--                                                                     0 --CH.sub.3                                                                          DCB                                                                              n/a   <1                                      __________________________________________________________________________

The data in Table I show that LINK groups, as described, which contain abulky Q-R_(q) group adjacent to the -O-CO-group, provide for improvedresistance to hydrolysis when compared to linking groups containing amethylene Q-R_(q) group of the type described in column 12 of U.S. Pat.No. 4,248,962. The larger the t_(1/2) of hydrolysis, the greater will bethe stability of the link during preprocessing storage of photographicelements containing compounds of the type CAR-LINK-PUG. For example,multilayer coatings containing Compound C-2 or an equimolar amount ofCompound 4 were kept for two weeks at 49° C. and 50% relative humidity,then extracted to determine the amounts of coupler compound remainingintact. It was found that about 20% of Comparison Compound C-2 was lostwhile Compound 4 of the invention was stable to these conditions and wasretained. This in-film test confirms the trends predicted by thesolution hydrolysis relative rates shown in Table I.

Data in the last column of Table I indicates that increasing the bulk ofthe Q-R_(q) group generally provides for a desirably faster PUG release,although full control of PUG release timing also depends on the choiceof other groups in the LINK structure.

EXAMPLES 12-25:

Photographic elements were prepared by coating the following layers on acellulose ester film support (amounts of each component are indicated inmg/m²):

    ______________________________________                                        Emulsion Layer 1:                                                                           Gelatin - 2691; red-sensitized                                                silver bromoiodide (as Ag) - 1615;                                            yellow image coupler dispersed in                                             dibutyl phthalate                                               Interlayer:   Gelatin - 624; didodecylhydro-                                                quinone - 113                                                   Emulsion Layer 2:                                                                           Gelatin - 2691; green-sensitized                                              silver bromoiodide (as Ag) - 1615;                                            cyan image coupler dispersed in                                               dibutyl phthalate; DIR compound of                                            Table I dispersed in N,N--diethyl-                                            dodecanamide and coated at a level                                            sufficient to provide a contrast                                              to red light of 0.8 after a                                                   stepwise green light exposure and                                             processing.                                                     Protective    Gelatin - 5382; bisvinylsulfonyl-                               Overcoat      methyl ether at 2% total gelatin.                               ______________________________________                                    

Structures of the image couplers are as follows: ##STR31##

Strips of each element were exposed to green light through a graduateddensity steptablet, or through a 35% modulation fringe chart forsharpness measurements, and then developed 3.25 minutes at 38° C. in thefollowing color developer, stopped, washed, bleached, fixed, washed anddried.

    ______________________________________                                        Color Developer                                                               ______________________________________                                        Distilled Water       800    mL                                               Sulfuric Acid         2.0    mL                                               Potassium Sulfite     2.0    g                                                CD-4*                 3.35   g                                                Potassium Carbonate   30.0   g                                                Potassium Bromide     1.25   g                                                Potassium Iodide      0.6    mg                                               Distilled Water       to 1   L                                                Adjust pH to 10.0                                                             ______________________________________                                         *4-amino-3-methyl-N--ethylN--hydroxyethylaniline sulfate.                

Processed images were read with red light to determine the contrast andAMT acutance. From plots of AMT acutance vs. the logarithm of thecontrast for variations in the coated level of each DIR compound, theacutance was determined at a contrast of 0.8. The acutance value forcomparison compound C-1 was subtracted from each AMT value to providethe relative sharpness value reported as AMT in Table I. AMTcalculations employed the following formula in which the cascaded areaunder the system modulation transfer curve is shown in equation (21.104)on p. 629 of the "Theory of the Photographic Process", 4th Edition,1977, edited by T. H. James:

    AMT=100+66 log [cascaded area/2.6696M]

where the magnification factor M=3.8 for the 35 mm system AMT. The useof CMT acutance is described by R. G. Gendron in "An Improved ObjectiveMethod for Rating Picture Sharpness: CMT Acutance" in the Journal of theSMPTE, Vol. 82, pp. 1009-12 (1973). AMT is a further modification of CMTuseful for evaluating systems which include the viewing of a positiveprint made from a negative.

                                      TABLE II                                    __________________________________________________________________________    Example Compd.                                                                             Link                                                                             Q--R.sub.q                                                                           n R.sub.3                                                                             PUG                                                                              AMT                                         __________________________________________________________________________    12 Comparison                                                                         C-6  L-2               PMT                                                                              0                                           13 Comparison                                                                         C-7  L-3               PMT                                                                              2.0                                         14 Comparison                                                                         C-2  L-1                                                                              --CH.sub.2 --                                                                        0 --Ph  PMT                                                                              2.4                                         15 Invention                                                                          1    L-1                                                                              --CH(CH.sub.3)--                                                                     0 --CH.sub.3                                                                          PMT                                                                              3.5                                         16 Invention                                                                          4    L-1                                                                              --C(CH.sub.3).sub.2 --                                                               1 --Ph--3-Cl                                                                          PMT                                                                              4.9                                         17 Comparison                                                                         C-8  L-2               DPB                                                                              0                                           18 Comparison                                                                         C-9  L-1                                                                              --CH.sub.2 --                                                                        0 --Ph  DPB                                                                              0.8                                         19 Invention                                                                          5    L-1                                                                              --CH(CH.sub.3)--                                                                     0 --CH.sub.3 --                                                                       DPB                                                                              2.5                                         20 Comparison                                                                         C-10 L-2               MBMT                                                                             0                                           21 Comparison                                                                         C-11 L-1                                                                              --CH.sub.2 --                                                                        0 --Ph  MBMT                                                                             1.8                                         22 Invention                                                                          7    L-1                                                                              --CH(CH.sub.3)--                                                                     0 --CH.sub.3                                                                          MBMT                                                                             4.5                                         __________________________________________________________________________

It can be seen from the AMT acutance values in Table II that the use inphotographic elements of compounds of the invention, which contain abulky Q-R_(q) group in the LINK moiety, leads to improved sharpness fromthe combination of groups over that attained by using closely relatedgroups in comparison DIR compounds which release the same developmentinhibitor PUG moieties. ##STR32##

                                      TABLE III                                   __________________________________________________________________________            Compd.              Fog level at Devt. Time (min.)                    Example Added                                                                              mg/m.sup.2                                                                        Q--R.sub.q                                                                           R.sub.3                                                                           1.00                                                                             1.75                                                                              2.50                                                                              3.25                                   __________________________________________________________________________    23 Control                                                                            None --  --     --  n/a*                                                                             n/a n/a 0.34                                   24 Comparison                                                                         C-12 48  --CH.sub.2 --                                                                        --Ph                                                                              0.30                                                                             1.22                                                                              2.03                                                                              2.56                                   25 Invention                                                                          8    116 --N(CH.sub.3)--                                                                      --CH.sub.3                                                                        n/a                                                                              n/a n/a 0.24                                   __________________________________________________________________________     *n/a: data not available                                                 

The benefits to be gained from this invention are clearly demonstratedby the data in Table III. They show that comparison Compound C-12, ofthe type described in column 12 of U.S. Pat. No. 4,248,962, hydrolyzesrapidly under development conditions to produce a strong fogging agent,while incorporating Compound 8 of the invention, even at a much higherlevel, results in an image with less fog than the no-DIR control.

The release of a useful compound from a carrier compound (A) can also beuseful in other applications wherein controlled release is desired.Initiation of such release may be triggered by hydrolysis or redoxreactions, for example. For example, the described -LINK-PUG group canrelease, for example, pharmaceutically useful moieties, including drugs,dyes, analytical agents, agricultural chemicals, and other usefulmoieties.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

What is claimed is:
 1. A photographic element comprising a support, atleast one photographic silver halide emulsion layer and at least onecompound (A) represented by the formula CAR-LINK-PUG where CAR is acarrier moiety capable of releasing LINK-PUG during photographicprocessing upon reaction with oxidized developing agent; LINK-PUG is inturn capable of releasing a photographically useful group (PUG) by anintramolecular nucleophilic displacement reaction; and LINK-PUG isrepresented by the formula: ##STR33## wherein Q is N or CR_(z) ;R_(q) isalkyl, cycloalkyl, heterocyclyl or aryl, or R_(q) together with R₁, R₂or R_(z) can represent the atoms necessary to complete a non-aromaticring; R_(z), R₁ and R₂ are independently alkyl, cycloalkyl,heterocyclyl, aryl or hydrogen; R₃ is alkyl, cycloalkyl, heterocyclyl oraryl; n is 0 or 1; and the LINK moiety enables increased resistance tohydrolysis.
 2. A photographic element as in claim 1 wherein the LINK-PUGgroup is represented by the formula: ##STR34## wherein R₄ is alkyl,cycloalkyl, heterocyclyl or aryl and PUG is a photographically usefulgroup.
 3. A photographic element as in claim 1 wherein the LINK-PUGgroup is represented by the formula: ##STR35## wherein R₄ is alkyl,cycloalkyl, heterocyclyl or aryl and PUG is a photographically usefulgroup.
 4. A photographic element as in claim 1 wherein the LINK-PUGgroup is represented by the formula: ##STR36## wherein R₄ is alkyl,cycloalkyl, heterocyclyl or aryl and PUG is a photographically usefulgroup.
 5. A photographic element as in claim 1 wherein the compound (A)is a coupler represented by the formula: ##STR37## wherein COUP is acoupler moiety;R₅ is an electron donating group or an electronwithdrawing group; and, Q is a releasable development inhibitor moiety.6. A photographic element as in claim 1 wherein the compound (A) is##STR38##
 7. A photographic element as in claim 1 wherein thephotographically useful group is a releasable development inhibitor,developing agent, development accelerator, bleach inhibitor, bleachaccelerator, dye, dye precursor, stabilizer, coupler, nucleator, fixingagent, image toner, hardener, antifoggant, or ultraviolet radiationabsorber.
 8. A process of forming a photographic image which comprisesdeveloping an exposed photographic silver halide emulsion layer with acolor developing agent in the presence of a compound (A) as defined inclaim
 1. 9. A process of forming a photographic image as in claim 8wherein the compound (A) is a coupler as defined in claim
 4. 10. Aprocess as in claim 8 wherein the compound (A) is: ##STR39##